In the U.S. about 23 million women aged 50-74 are overdue for recommended biennial screening mammography. Repeated annual screening is considered optimal by some experts and even more women would be overdue by this standard. The reduction in breast cancer mortality expected from screening mammography requires repeated mammogram use, so women who do not have a mammogram every 1-2 years are at risk for developing advanced stage or incurable breast cancers. NHIS 2005 data show a significant drop in mammograms gotten in the prior 24 months. Between 2000 and 2005, rates dropped for women aged 50-64 from 78.6 to 71.8% and for those >65, from 68 to 63.8%. Those most affected had higher incomes, private insurance and a usual source of care. Despite strong evidence that mail and telephone outreach to women can increase mammography rates, few health care delivery organizations have adopted comprehensive outreach programs, especially ones including a telephone component. Reasons for this include: 1) uncertainty about the optimum outreach strategy and long-term effectiveness; 2) absence of feasible, replicable models for use in large organizations; and 3) cost and cost-effectiveness data to guide the decisions on implementation. To address these concerns this study aims to identify the most effective and cost effective of the outreach strategies that studies have been shown to be effective or promising. We propose to randomize all women age 51-84 enrolled in a large group model HMO (n=23,000) to 1 of 3 intervention arms. We will continue to enroll new HMO members and to deliver the interventions over a 4-year period to assess long-term outcomes. The interventions are: 1) a reminder letter only (RL) (usual care for this HMO); 2) a reminder letter followed by a reminder phone call to nonresponders (RL-RC) that includes an opportunity to schedule a mammogram; and 3) a reminder letter followed by an enhanced, tailored telephone counseling (ETTC) to nonresponders (RL-ETTC) that includes motivational interviewing, barrier-specific counseling, and an opportunity to schedule a mammogram. Our aims are to: 1) compare the effectiveness of the 3 interventions in increasing adherence to screening mammography guidelines (mammogram every 1-2 years) each year for 4 years; 2) Identify ways to improve the efficiency and sequencing of the interventions by identifying patient factors and intervention mechanisms associated with increased intervention effectiveness; and 3) to determine the incremental cost per unit increase in on-time mammography utilization of the 2 telephone counseling arms compared to the mailed reminder only intervention. We hypothesize that ETTC intervention will be associated with a higher prevalence of mammography within 24 months than the brief telephone reminder intervention, and both telephone interventions will be more effective than the mailed reminder alone for each for the 4 intervention years and that the effectiveness of the intensive telephone intervention will increase each year due to the cumulative effect of the education and motivation it provides.